Re: [PATCH 01/18] usb: dwc3: Reserve Higher Bandwidth for HS Periodic EPs

[AKASH KUMAR]

Hi,

On 2/6/2025 11:19 PM, Konrad Dybcio wrote:
> On 6.02.2025 12:15 PM, Akash Kumar wrote:
> > On targets using synopsys usb dwc3 controller, it is observed while testing
> > multiple audio devices, a glitch is observed during testing.
> > As per dwc datasheet,By default, HC reserves 80% of the bandwidth
> > for periodic EPs which can be increased with GUCTL Bit 16.
> It is observed a glitch is observed.. please massage this paragraph
> a bit.
Sure.
> > Add quirk to set GUCTL register BIT 16 to accommodate higher
> > bandwidth for 2 isoc eps.
> >
> > If this bit is set, the bandwidth is relaxed to 85% to
> > accommodate two high speed, high bandwidth ISOC EPs.
> > USB 2.0 required 80% bandwidth allocated for ISOC traffic. If
> > two High-bandwidth ISOC devices (HD Webcams) are
> > connected, and if each requires 1024-bytes X 3 packets per
> > Micro-Frame, then the bandwidth required is around 82%. If
> > this bit is set, then it is possible to connect two Webcams of
> > 1024bytes X 3 paylod per Micro-Frame each. Alternatively, you
> > might need to lower the resolution of the webcams.
> > This bit is valid in Host and DRD configuration and is used in
> > host mode operation only.
> > Set this bit for host mode uvc uac usecases where two isoc eps
> > are used and flicker is seen.
> Re-format your commit text to wrap at ~72 characters
Ok.
> > Signed-off-by: Akash Kumar <quic_akakum@xxxxxxxxxxx>
> > ---
> >   drivers/usb/dwc3/core.c | 11 +++++++++++
> >   drivers/usb/dwc3/core.h |  4 ++++
> >   2 files changed, 15 insertions(+)
> >
> > diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
> > index dfa1b5fe48dc..7e55c234e4e5 100644
> > --- a/drivers/usb/dwc3/core.c
> > +++ b/drivers/usb/dwc3/core.c
> > @@ -1461,6 +1461,14 @@ static int dwc3_core_init(struct dwc3 *dwc)
> >   		dwc3_writel(dwc->regs, DWC3_GUCTL1, reg);
> >   	}
> >   
> > +	if (dwc->revision >= DWC3_REVISION_250A) {
> > +		if (dwc->dwc3_guctl_resbwhseps_quirk) {
> > +			reg = dwc3_readl(dwc->regs, DWC3_GUCTL);
> > +			reg |= DWC3_GUCTL_RESBWHSEPS;
> > +			dwc3_writel(dwc->regs, DWC3_GUCTL, reg);
> > +		}
> > +	}
> > +
> >   	dwc3_config_threshold(dwc);
> >   
> >   	/*
> > @@ -1818,6 +1826,9 @@ static void dwc3_get_properties(struct dwc3 *dwc)
> >   	dwc->dis_split_quirk = device_property_read_bool(dev,
> >   				"snps,dis-split-quirk");
> >   
> > +	dwc->dwc3_guctl_resbwhseps_quirk = device_property_read_bool(dev,
> > +				"snps,dwc3_guctl_resbwhseps_quirk");
> This needs a dt-bindings entry. Also, underscores are forbidden in property
> names, use hyphens instead.

Will update in V2.

Thanks

Akash